Companion to ff92706 (drift test fix). The inline handler moves to a
module exporting { buildRouter, getVersion, getName }, pre-built once
at startup and mounted bare on apiRouter — the exact shape the drift
test walker now recognizes. Dockerfile builder stage switches to
npm ci --omit=dev for deterministic builds. Tests: 12/12 across the
three new/updated suites; full suite 1837/1837.
